15
2.3.4 Analyzer calibration by outside air
Outside air calibration of the analyzer should be performed:
when the device is new;
once a shift (8 h);
after replacement of electrolyte, membrane and teflon film.
Calibration of the analyzer is performed in the outside air at temperatures be-
tween +15 °С and +35 °С and a 100 % relative humidity. It is more convenient to
perform calibration at room temperature.
Prior to calibration, the analyzer, with AA-type alkaline batteries installed,
should be held at room temperature for at least 1 h. The analyzer may be left
switched on. Submerge the sensor fully in distilled water of room temperature for a
minimum of 10 min.
Rinse the sensor in distilled water, shake off water drops from the sensor
membrane and put the sensor in the cone flask with a water layer 3 to 5 mm, as
shown in Fig.2.1. Position the flask at an angle of 30 to 45° to the horizontal for the
remaining water to flow off the membrane.
Fig. 2.1 − Position of the sensor inside the flask for analyzer calibration
Wait for 10 min before performing the outside air calibration steps which fol-
low.
1
Press the
CAL
button twice. The
c1
character will appear on the display,
showing the entry into the outside air calibration mode.
2
Press the
ENTER
button. The analyzer will display DOC readings corre-
sponding to the table of 100 % humidity air oxygen solubility for analyzer-measured
temperature, with allowance for the atmospheric pressure at the time of calibration,
e.g.
c8.38 mg/dm
3
.
3
Wait at least
8 s
before pressing
ENTER
once again. The
donЕ
caption
will briefly appear on the display and the analyzer will go into the measuring mode.
It means the outside air calibration mode is completed and the analyzer is calibrat-
ed.
Sensor
Water
Flask
